1. Field of the Invention
The present invention relates to a turbocharged internal combustion engine and, more particularly, to an air-fuel ratio controller for use in such an engine.
2. Description of the Prior Art
A conventional air-fuel ratio controller regulates air-to-fuel ratio by controlling air manifold pressure as a function of gas manifold pressure and engine speed. While such a controller maintains a relatively constant air-to-fuel ratio for a wide range of loads, the ratio provided by such a controller occasionally deviates from an optimum value. One such occasion arises when fuel heating values vary. Accordingly, a need for an air-fuel ratio controller which is capable of correcting for varying fuel heating values has been recognized.